Mars: Formation and Evolution of the Late Amazonian Latitude-Dependent Ice-Rich Mantle Layer
Lunar and Planetary Institute
Great Room and Berkner DEF
Houston, Texas March 15-16, 2003
Saturday: March 15, 2003:
Introduction and Background: Jim Head and Sasha Basilevsky
1) Recognition of latitude-dependent processes and deposits on Mars:
Viking and other early observations of latitude-dependent deposits and terrain softening; early theories for origin; recognition and documentation in MOLA and MOC data.
"Early recognition of latitude-dependent dust processes from pre-MGS data"
"Detection of a latitude-dependent deposit in MOLA and MOC data: Data analysis techniques and characterization"
"Detection of latitude-dependent dissected layer in MOC data: Relationship to MOLA topographic properties"
Discussion: Comparison of the different techniques and definition of deposits.
2) Characterization and relation to geologic features:
What is it, its thickness, its internal stratigraphy? What is its latitude distribution? What different geological features seem to be correlated (e.g., gullies, patterned ground, polygons, basketball terrain, etc)?
"Distribution of geologic features associated with the latitude-dependent mantle and evidence for its decay"
"Distribution of gullies and debris flows by melting of near-surface ground ice at high obliquity"
"Microclimates (local geometry-dependent condensation, sublimation and melting) and their relation to the latitude-dependent layer"
3) Characteristics in Odyssey data and relation to present stability of ice:
What is the interpretation of the Odyssey GRS/NS data and how do they correlate with layer characteristics? What is present stability of ground ice? How does this match the distribution and characteristics of the LDL? How to distinguish between simple current stability and pre-existing deposits?
"Mars Odyssey gamma-ray spectrometer experiment results and the presence of water and ice on Mars"
"Current knowledge of the global distribution of hydrogen on Mars and implications for the presence and nature of ground ice"
"Odyssey neutron spectrometer data in the southern hemisphere: Assessment of the margin of near-surface ice deposits and correlation with MOLA and MOC data"
"Latitude-dependent aspects determined from Mars Odyssey HEND data"
"Theory of ground ice on Mars and implications to the neutron leakage flux"
6:00 PM: Reception
Sunday: March 16, 2003:
4) Stratigraphy, thickness, present state, and relation to pre-existing geologic units:
What is the relationship to pre-existing units? What evidence do we have for its physical properties? How does this help to constrain origin?
"Distribution of viscous flow features on the surface of Mars and implication for the characteristics and behavior of a latitude-dependent layer"
"Constraints on the thickness of a volatile-rich layer based on numerical models of viscous creep deformation of ice-rich permafrost"
"Thermophysical properties of the dissected mantle"
5) Age and relation to polar deposits:
What is the evidence for the age of the LDL? What is the stratigraphic evidence? What do crater counts tell us? What is the stratigraphic evidence for the relation to polar deposits? What are the implications for the age of the LDL?
"Impact crater morphologies in the latitude-dependent layer"
"Characteristics and crater-like features of the high-latitude mantle in the northern lowlands of Mars"
"Stratigraphic relationship of the latitude-dependent layer to Late Amazonian polar related deposits"
"Dating very recent geological activity on Mars using crater size-frequency distribution data"
6) Potential causes of the origin, emplacement mechanisms and evolution of the latitude-dependent layer:
What is the set of conditions that must be met by any theory for LDL origin? What is the range of models that might meet this set of conditions? What is the relation to climate and atmosphere? What is the range of behavior of water and dust in various paleoclimate scenarios? What is the relation to astronomical/orbital cycles? What is the range of behavior of water and dust in various astronomical cycle scenarios?
Jim Head and Jack Mustard:
"Summary of observations on the latitude-dependent layer and theories of origin"
Mike Mischna, John Wilson, and Mark Richardson:
"Orbital forcing of martian water and CO2 cycles: A general circulation model study with simplified volatile schemes"
"The response of martian atmospheric and crustal H2O to the emplacement and removal of depositional mantles"
7) Synthesis and future directions: Discussion:
Is there a LDL or are we just seeing ice stability features and surface creep? What are the firm observational characteristics that must be considered for the origin of the LDL? What is the range of hypotheses that account for these observational characteristics? What new data and observations are required to further characterize and understand the LDL?